Many types of catheters have been developed for treating problems and diseases of body systems including the vascular, pulmonary, lymphatic, urinary, and other systems that include one or more body lumens. Such catheters advantageously provide treatment by generally non-invasive techniques by permitting manipulation of distal features of such catheters from their proximal ends. These catheters may be made up of many components with properties selectively chosen for specific functions. And as a result, it is generally desirable to combine different components to obtain particular control aspects of such catheters. Generally, polymeric materials are used for such catheters because of medical use conditions and sanitation requirements and the like.
For a variety of reasons it may be necessary to provide catheters with side holes or apertures that extend transverse to the catheter's lumens. For example, in diagnostic catheters, a diagnostic contrast medium is injected through the tip and side holes to obtain a good cloud distribution. A well distributed cloud is particularly advantageous when a catheter pigtail is used to flush the heart chambers with a contrast medium. In other cases holes may be used to create a port for guidewires. In addition, holes are employed in filter-wires to allow blood cells to pass through the filter.
Conventional techniques for producing side holes in catheters include punching or drilling. One problem with such techniques is that the resulting holes generally have sharp edges where they meet the outer surface of the catheter. Sharp edges are undesirable because they may scrape or otherwise damage the vessel wall as the catheter is inserted into position. More generally, holes or other features with a wide variety of different shapes and orientations with respect to the catheter can be difficult to produce by conventional techniques.
In recent years lasers have been shown to be a valuable means for performing high-precision micromachining because of their directionality, coherence, high intensity and high photon energy. In particular, lasers have been employed to produce voids or thru-holes by a process of ablation. In contrast to punching or drilling techniques, the voids or thru-holes formed by ablation may be circular or non-circular in shape. In ablation processes lasers, often operating at ultraviolet wavelengths, provide photons with sufficient energy to excite the electrons that form the molecular bonds of certain workpiece materials such as polymeric materials. Sufficient excitation of the bonding electrons with a beam results in the localized disassociation of the material with little or no heating of the workpiece.
Accordingly, it would be desirable to provide an improved method and apparatus for ablating material from a workpiece so that a variety of differently configured features may be formed.